Many known surveillance systems have used a closed circuit television approach. In such an approach, a number of video cameras are mounted at different points; video coaxial cable is routed from each of the cameras to a centralized guard station; the outputs of the cameras are fed to video display monitors at the guard station. A guard typically monitors the closed circuit television displays in real time. The outputs of the video cameras may also be recorded on a tape which is typically overwritten after some specified amount of time. This approach relies on human monitoring of the closed circuit television displays to detect breaches in security. A guard is hired to sit at the guard station and continuously monitor multiple video screens. This approach is not reliable enough to achieve a high level of security, as guards hired to look at monitors all day long have a tendency to fall asleep, e.g., due to boredom. In some cases, the guards, who are not necessarily highly paid, have taken on the security guard job as a second job, and have a tendency to nap or fall sleep when left alone. In some cases, guards become pre-occupied with other distractions, e.g., newspapers, magazines, talking on the phone, watching or listening to a ball game, receiving a delivery package, etc., and may be distracted at a critical moment missing a security breach. Sometimes, guards also have to temporarily leave their station, e.g., to physically “make the rounds” checking out a number of designated sites and/or locks.
A single guard is limited as to how many monitors he/she can simultaneously view effectively before becoming overloaded. Therefore in surveillance systems including a large number of closed circuit television cameras, one approach employed to attempt to prevent guard overload is to hire a large number of guards, each guard being responsible for a fraction of the total number of displays. In this way, each of the displays can be simultaneously viewed with a higher level of confidence that security breaches will be detected. However, this approach is costly and still not highly reliable, since for the approach to achieve highly effective coverage all the guards need to continuously remain vigilant, an unlikely scenario. Another approach employed is to use a limited number of guards and switch between cameras; however, this results in incomplete continuous coverage increasing the likelihood of an undetected security breach.
Although it might seem that replacing humans with a fully computerized system might seem to be a viable alternative to increasing reliability and overall effectiveness, there is another problem which results. Computer programs have not reached the level of sophistication to match the judgment of a human; humans can adapt and adjust more readily to changes, different scenarios, and grey areas. Humans can also more readily distinguish suspicious individuals and patterns of suspicious behavior more readily than computers, e.g., profiling that there is no reason for certain suspicious looking individuals to be lingering at the border of a secure site at a certain time of day or performing some suspicious activity, e.g., photographing the site.
In some other known surveillance systems, closed circuit television cameras are installed and connected to recording devices which tape the camera video; however, a guard is not stationed to continuously monitor the video. Rather, the video is played back and reviewed after an event, e.g., after a crime has occurred and been detected by other means, in order to try to identify the responsible individuals. Such an approach is useful for forensic crime detection, but is not well suited for identifying the security breach in real-time and being able to take actions to stop the criminal activity.
In view of the Sep. 11, 2001, terrorist events and other worldwide terrorist activities, the reliability of the above described approaches is unacceptable for many critical sites. There is a need for more reliable surveillance methods and apparatus that remove some of the uncertainty associated with having to count so much on the guard. It would also be beneficial if new methods and apparatus of security surveillance are able to detect security breaches in real-time, so that actions can be taken before damage is done.
In view of the above discussion there is a need for new methods and apparatus of surveillance systems that provide a high level of reliability while maintaining continuous coverage of the surveillance area. It would be beneficial if such systems use approaches that take into account deployment and ongoing costs to provide economically feasible alternatives to currently deployed approaches. Cost effective approaches would be attractive for deployment at other sites where security is needed, but the level of security required is not quite as high, e.g., an office, store, or home site.
In surveillance systems including a larger surveillance area, there is typically a trade-off that needs to be made between resolution and coverage area. One would like to have high resolution cameras everywhere so that objects could be clearly identified and distinguished. Typically, this has required a large number of expensive cameras to cover a small section to obtain enough resolution and a very large number of expensive cameras to cover a large area. This approach can become economically infeasible for many deployments. Typically, system designers have traded-off resolution to satisfy cost budgets, e.g., reducing the number of cameras deployed for a given area or selecting a cheaper camera with lower resolution and/or capabilities. Another problem with a large number of cameras is the issue of bandwidth. Continuous closed circuit television streamed back to a guard site for a large number of cameras, e.g., via dedicated cables or over wireless air links tends to consume a lot of bandwidth, which may not be available or may be very costly. One approach used is to sacrifice resolution or picture quality to increase coverage area, for the same amount of bandwidth. It would be beneficial if methods and apparatus were developed which did not require the system designer to have to make such sacrifices.
Another problem with a surveillance system including a large number of cameras is the reliability issue. As the number of cameras in the system increases, it becomes more likely that at any given time a camera will have failed and be inoperative somewhere in the system, resulting in an uncovered surveillance region. One approach used to address this issue is to deploy for each camera a redundant camera to serve as a back-up. However, this approach becomes very expensive, and is infeasible in many applications from a cost perspective.
In current large scale site deployments, it has been typical for the surveillance system to be custom designed with one set of cameras, camera links, control systems, software packages, etc., being used for one site and a different set of elements being used at another site. Individually designing and integrating such a custom system can be very labor intensive and tends to contribute to system unreliability, as each custom system when deployed has no past track record of operation, and it is to be expected that bugs and deficiencies in the design will show up during operation. In view of the above, it would be beneficial if new methods and apparatus of security systems were developed which tended toward a reusable design approach and a high commonality of hardware/software. Approaches which allowed the basic surveillance system to be readily adapted to different surveillance landscapes and/or sizes without fundamentally altering the system would allow a system design to be tested and qualified, and the qualified system design to be reused in many different deployments with a high level of confidence in reliability.